{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lecture 5

# lecture 5 - CS 188 Artificial Intelligence Spring 2010...

This preview shows pages 1–7. Sign up to view the full content.

1 CS 188: Artificial Intelligence Spring 2010 Lecture 5: CSPs II 2/2/2010 Pieter Abbeel – UC Berkeley Many slides from Dan Klein 1 Announcements square4 Project 1 due Thursday square4 Lecture videos reminder: don’t count on it square4 Midterm square4 Section: CSPs square4 Tue 3-4pm, 285 Cory square4 Tue 4-5pm, 285 Cory square4 Wed 11-noon, 285 Cory square4 Wed noon-1pm, 285 Cory 2

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 Today square4 CSPs square4 Efficient Solution of CSPs square4 Search square4 Constraint propagation square4 Local Search 3 Example: Map-Coloring square4 Variables: square4 Domain: square4 Constraints: adjacent regions must have different colors square4 Solutions are assignments satisfying all constraints, e.g.: 5
3 Constraint Graphs square4 Binary CSP: each constraint relates (at most) two variables square4 Binary constraint graph: nodes are variables, arcs show constraints square4 General-purpose CSP algorithms use the graph structure to speed up search. E.g., Tasmania is an independent subproblem! 6 Example: Cryptarithmetic square4 Variables (circles): square4 Domains: square4 Constraints (boxes): 7

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Example: Sudoku square4 Variables: square4 Each (open) square square4 Domains: square4 {1,2,…,9} square4 Constraints: 9-way alldiff for each row 9-way alldiff for each column 9-way alldiff for each region Example: The Waltz Algorithm square4 The Waltz algorithm is for interpreting line drawings of solid polyhedra square4 An early example of a computation posed as a CSP square4 Look at all intersections square4 Adjacent intersections impose constraints on each other ? 10
5 Varieties of CSPs square4 Discrete Variables square4 Finite domains square4 Size d means O( d n ) complete assignments square4 E.g., Boolean CSPs, including Boolean satisfiability (NP-complete) square4 Infinite domains (integers, strings, etc.) square4 E.g., job scheduling, variables are start/end times for each job square4 Linear constraints solvable, nonlinear undecidable square4 Continuous variables square4 E.g., start-end state of a robot square4 Linear constraints solvable in polynomial time by LP methods (see cs170 for a bit of this theory) 14 Varieties of Constraints square4 Varieties of Constraints square4 Unary constraints involve a single variable (equiv. to shrinking domains): square4 Binary constraints involve pairs of variables: square4 Higher-order constraints involve 3 or more variables: e.g., cryptarithmetic column constraints square4 Preferences (soft constraints): square4 E.g., red is better than green square4 Often representable by a cost for each variable assignment square4 Gives constrained optimization problems square4 (We’ll ignore these until we get to Bayes’ nets) 15

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
6 Real-World CSPs square4 Assignment problems: e.g., who teaches what class square4 Timetabling problems: e.g., which class is offered when and where?
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern